This invention relates generally to a multi-speed drop leg mechanical jack, and more particularly, to a multi-speed drop leg mechanical jack for use with a trailer.
In the mechanical jack industry, and specifically where mechanical jacks are used with trailers, there is a continuing need to have user-friendly jacks that provide a commercially valuable balance of jack speed, lifting and lowering capabilities, ease of cranking and overall performance for both loaded and unloaded trailers. In mechanical jacks these variables are best overcome by selecting the appropriate gears by which the mechanical jack will operate, as well as anticipating the type of trailer that will be used with the jack.
In many instances, it is desirable for mechanical jacks to have multiple gear ratios that not only have the capacity to handle relatively heavy loads, but also have the ability to handle small and midsize loads while maintaining sufficient and commercially acceptable cranking speeds without excessive force required.
In addition, it is oftentimes desirable to be able to quickly provide elongation of the mechanical jack, such as in a drop leg, where there is not any mechanical cranking required in order to have a significant amount of jack elongation or contraction in a short amount of time, such as at the beginning or completion of the lifting process.
Moreover, it is also desirable to provide an efficient way to change from one operating gear of the jack to another. To the extent that the operator of the jack can better use the crank of the jack to facilitate faster and smoother changes of operating gears, the crank will be considered to be advantageous. It is a continuing design goal to have a crank that facilitates operator use of the mechanical jack to which it is connected, in order to provide improved cranking and improved changing from one operating gear to another.
Therefore, it would be advantageous to have a mechanical jack typically used with trailers that has a functional combination of several working gears as well as a drop leg feature. It would be particularly desirable if the drop leg feature was considered when selecting the working gears of the jack. It would also be advantageous to have a crank or handle for use with a mechanical jack that assists in both effective raising and lowering of the jack, as well as efficient transition from one working gear to another.